Evaluate if optimizing the performance of the new resolve-implementation is necessary

[elkowar]

The resolve-implementation introduced in #26 is likely to bring significantly more overhead, as every value - even single, primitive values - are now handled as a List of possible VarRefs.
This could be optimized, at the cost of readability.

Acceptance criteria

• A better understanding of the performance implications of the current implementation is gained
• If concluded that optimizations would make sense, the code is thusly optimized implemented

[elkowar]

Given that there haven't been any noticable performance issues, this can be closed.